Thermosetting acrylic resins and their use as binders in dental filling compositions

ABSTRACT

Bisphenol-A-bis(2,3-dimethacrylatopropyl ether) and the adduct of methacrylic acid and triglycidyl ether of trihydroxy biphenyl are utilized as binders for dental restorative compositions.

United States Patent [1 1 Stofieyet al. Nov. 27, 1973 [54] THERMOSETTING ACRYLIC RESINS AND [58] Field of Search 32/15 THEIR USE AS BINDERS IN DENTAL FILLING COMPOSITIONS References Cite 76 Inventors: Donald G. Stofiey, 15120 Hollis St., UNITED STATES PATENTS Hacienda Heights, Calif. 91745; 3,452,437 1/1969 Chang 32/ 15 Henry L I ea, Jr. Sierra Madre I Rehberg et Blvd., San Marino, Calif. 91108 Filed: July 14, 1972 Appl. No.: 272,061

Related US. Application Data Division of Ser. No. 102,044, Dec. 28, 1970, Pat. No.

US. Cl. 32/15 Int. Cl A6 1k 5/02 Primary ExaminerRobert Peshock Attorneylr0ns, Sears & Santorelli [57 ABSTRACT Bisphenol-A-bis(2,3-dimethacrylatopropyl ether) and 8 Claims, No Drawings THERMOSETTING ACRYLIC RESINS AND THEIR USE AS BINDERS IN DENTAL FILLING COMPOSITIONS This application is a division of Ser. No. 102,044 filed Dec. 28, 1970 and now US. Pat. No. 3,721,644.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is related to certain aromatic, thermosetting acrylic resins and their use as binders in dental filling compositions for the direct filling of teeth.

2. Description of the Prior Art Thermosetting acrylic esters of bisphenolic compounds have been used in the past for a variety of purposes, including, for example, the pottingof electrical coils. Many such compounds are disclosed in US. Pat. No. 2,890.202.

Certain specific acrylic resins have been used asbinders for dental restorative purposes. In particular, the compounds disclosed in Bowen in US. Pat. Nos. 3,066,112 and 3,179,623 have been used with some success. Chief among the resins of Bowen is a compound having the formula:

which is glycidyl methacrylate derivative of bisphenol- A and which is sometimes referred to as BIS-GMA. This compound has also been referred to as bisphenol- A-bis(3-methacrylato-Z-hydroxypropyl)ether.

While the general properties of BIS-GMA are quite good for dental restorative purposes, this resin is extremely viscous and sometimes tends to absorb undesirable amounts of water when used in wet environments, and has a gel time longer than that which is desirable for many purposes.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide thermosetting resins useful in molding compositions and which are particularly useful in dental restorative compositions, which have improved handling characteristics and higher crosslinked densities when compared to BIS-GMA, but still possess all of the favorable characteristics of BIS-GMA. It has been discovered that significantly improved thermosetting resins which are useful as binders indental restorative compositions are obtained from monomer compounds of the following formulae:

wherein each of R and R, may independently be hydrogen, lower alkyl, i.e., straight or branched chain alkyl of one to four carbon atoms, methyl being preferred, or halogen, chlorine being preferred; and

wherein R is hydrogen, lower alkyl, i.e., straight or branched chain alkyl of one to four carbon atoms, preferably methyl, or halogen, chlorine being preferred. The preferred meaning of R is methyl.

DESCRIPTION OF THE PREFERRED EMBODIMENTS R VII H3 ha I which may be named bisphenol-A-bis(2,3-dimethacrylatopropyl ehter); and the second is a compound of the formula;

V acryl chloride in thepresence The compounds of ormulall The foregoing monomers yield thermosettingpolymers of increased crosslinked density over thoseprevi ously utilized by the prior art. The resins of the present I can be absorbed by the material.

The, acrylates of Formula I of this invention I As indicated, the monomeric polyacrylic resins'of this invention are utilized as binders in dental restor-' I I V I ative compositions. Typically, such. compositions coninvention have a much faster gel time than the prior art I i prepared byreacting BIS GMA 'with'anexcess of an,

as triethylamineor pyridine.

be prepared by reacting the triglycidylethergofgtrihy droxy biphenyl with-methacrylicacidin the presence or a catalyst such as a tertiary amine,itriphenylphosphine,-

of a tertiary amine such I of this invention rn'ay a or" triphenylantimony. .The: former. is commercially; I j

7 available as xoroxmrwhne xoPox-r/I, may be i used in its commerically availableform, it {contains 'a significantpercentage of ,higher'mo lecular weight ma 1 terial andundistillable coloredmattenthe presence of which tends to'impartundesirable color to the desired acrylate.product.,ltis preferable thatthe KOPOX -l71;

i be molecularly. distilled to. yield substantially. pure triglycidyl ether of trihydroxy biphenyl; j

The following, examples describing certain specific a I embodiments of the invention will: serve to furtherillustrate'the nature of he invention. e I i l 10 ml. of freshly distill'ed. rnethacryl chloride is 1 added dropwisetda solution of 260 g. ofbisphenol-A- bis( 3 methacrylate-2-hydroxypropyl)ether,440 ml. of' j dry methylene chloride and 170 ml; of triethylamine,

During the addition, the reaction mixture is keptat'a 7 J temperature between 10 and 15C. Following complee, tion of the'addition, the temperatureof the solution. is allowed to to room temperature during continuous'stirring and 'maintained-atthat temperature for approximately 30 minutes; Thereafter,f'- the amine salt formed istiltered off, and theremainingcake: washed with methylene chloride. The combined organic layer:

is washed with 0.1 normal hydrochloric acid until acidic, and then with water until neutral. After a final wash with water, it is dried over anhydrous sodium sulfate and the solvent removed by evaporation on a rotary evaporator at-2 mm/l-lg pressure. The residue is a colorless liquid of significantly less viscosity than BIS- GMA.

EXAMPLE 2 35.5 g. of the triglycidyl ether of trihydroxy biphenyl (obtained by the molecular distillation of KOPOX- 171), 24 g. of methacrylic acid and 0.6 ml. of triethyl- I tions without the use of any viscosity reducing diluents.

'be formulated into dental restorative filler composi- It is especially significantto note that the compound of Example 1 has significantly less water absorption ten- Qsnsir tl1@! ..BlS:QMA,-.

sist of approximately 65 -to" percent by weight of finely divided solid particles of a filler and about 25 to izedinto a curedresin. The finely divided ffille'r, may. g I g have a particle size generally in the range of the "1 mi eronto about microns The preferredrangeis rm f I a about 1 micron to 30 microns. The best resultsare ob-j tained where the inorganic filler istreated witha keying Q agent tofimprove the bondj betweenorganic polyi fmer biriderand t e surfaces otthe finelydividedifillfer f particle's. Keying agentslwhichhave beenifound highly suitable are the ethylenically unsaturated organosilane 3 e I finishingorkeyingagentswherefthefille'r is fused silica, Y

glass, aluminum Yoxide,;.0r crystalline quartz'and the' Q; binder systemisof the' type' describedflhe finelydi- Lvide dqfiller" may be treated withthe keying, a ent, for example, in the'man'nerl described inl, 1.8.7 Pat No. 3,066,l12" wherein an aqueous solution of tris'( 2 -;,l methoxyethox'y) vinylsilaneiis;catalyzedwithisodium; a hydroxide tofgive ajpHof 9'.31to:9.8,;and the filler treated with this solutiomfor example', one-half per-, I

cent of the silane beingused perweig'ht of fused quartz. f1 j A slurryso formed is driedatabout I25 C@dcooled. 1 I

' Although aluminum oxide in theform of fused alu'-, mina, having a: particlej'size of, 10 microns, to 5.0;mi-

be desirable to use the same .iin preparing anteriordenQ talfillings, as dentalfillingsusingaluminum oxide, due

"to its extreme hardness zandtabrasive characteristics,

can pick up marks from I a metal utensil "when rubbed against the same thus making suchdental fillings,from g the: standpoint; of? appearance, :"possibly undesirable where such markings might become visible toa casual: H observer. However, because'ofitheexcellent'wearresisef I tance of fillin'gsobtainedusing fused alumina, such fill-i q ings arehighlyisuitableforfillingteetliwhere anyamark'-- 1i, 1 I I ing, through the contact with utensils, is less likely to occur, and if it should occur would not be visibly appar ent to the casual observer.

Where more translucent filling materials are desired, as for the filling of anteriorteeth, glass beads, or a mixture of glass beads and quartz may be used.

The resins produced in accordance with Examples 1 and 2 are ready for use without dilution or treatment.

with a reactive diluent as has been necessary previ- I ously. About 0.5 to lpercent by weight based on the weight of hinder, or more, of an activator, such as, for

example, dimethyl-para-toluidine, may be added tothe resin. A suitable catalyst, such as, for example, I percent by weight benzoyl peroxide, based on the weight of binder, may be mixed" into the treated filler material. The filler material containing the catalyst and the resin containing the activator may then be thoroughly mixed together and promptly placed in a cavity to be filled.

The binder will polymerize at mouth temperature to harden the filling within about 10 minutes.

Other suitable activators include, inter alia, paratoluene sulfinic acid, para-tolyl diethanol amine and other tertiary amines which are well known in the art. The amount of activator to be used depends on the particular compound utilized and on the working time desired. Generally the activator will be present in amounts of less than 1 percent by weight of the monomers in the binder.

While benzoyl peroxide is a preferred catalyst, other peroxide catalysts might be used as is well known in this art. The catalyst should preferably be present in an amount ranging from 1 percent to 2 percent by weight based on the weight of the monomers present in the binder.

The solid fillings formed from the compositions of this invention have high compressive strengths which are well within the standards as set forth in American Dental Association Specification No. 9.

By way of illustration, the monomer compound of Example 1 is mixedwith 1 percent by weight of benzoyl peroxide, 0.l percent N,N-dimethyl-(p-toluidine). This resin mixture is then blended with a silica filler which has been silane treated in the manner described above in the proportion of 30 percent resin and 70 percent filler by weight. The resulting composition is placed in the prepared cavity of a tooth, a satisfactory gel forming in approximately 2% to 3 minutes. The compressive strength of the filling was 30,000 p.s.i. after minutes, 31,400 p.s.i. after 30 minutes, and 34,700 psi. after 1 hour according to American Dental Association Specification No. 9.

Also, the solubility and disintegration characteristics of the solid fillings, as judged by the same specification, are very low. All other characteristics of the compositions of this invention indicate a high utility as a dental restorative material. We claim:

1. In a method for the direct filling of a cavity in a tooth, which method includes filling said cavity with an initially liquid, settable filling material comprising a finely divided filler and a binder admixed therewith,

and thereafter permitting said .material to harden in situ, the improvement in such method comprising utilizing as the predominant component of said binder a thermosetting resin compound of the formula:

OH; R

tooth, which method includes filling said cavity with an initially liquid, settable filling material comprising a finely divided filler and a binder admixed therewith,

and thereafter permitting said material to harden in situ, the improvement in such method comprising utilizing as the predominant component of said binder a thermosetting resin compound of the formula:

wherein R is hydrogen, lower alkyl, or halogen.

6. A method as claimed in claim 5 wherein R is hydrogen.

7. A method as claimed in claim 5 wherein R is lower alkyl.

8. A method as claimed in claim 5 wherein R is methyl. 

2. A method as claimed in claim 1 wherein R and R1 are hydrogen.
 3. A method as claimed in claim 1 wherein R and R1 are lower alkyl.
 4. A method as claimed in claim 1 wherein R and R1 are methyl.
 5. In a method for the direct filling of a cavity in a tooth, which method includes filling said cavity with an initially liquid, settable filling material comprising a finely divided filler and a binder admixed therewith, and thereafter permitting said material to harden in situ, the improvement in such method comprising utilizing as the predominant component of said binder a thermosetting resin compound of the formula:
 6. A method as claimed in claim 5 wherein R is hydrogen.
 7. A method as claimed in claim 5 wherein R is lower alkyl.
 8. A method as claimed in claim 5 wherein R is methyl. 